EP2789723B1 - Method for wet treatment, in particular for washing, of laundry - Google Patents

Description

The invention relates to a method for wet treatment, preferably washing, of laundry according to the preamble of claim 1.

The wet treatment of laundry items is usually done by washing, rinsing and optionally at least one aftertreatment. One type of post-treatment may be neutralization.

The neutralization of the washed laundry items is required if, for example, due to treatment additives used in the washing process, for example detergents, an acidic or basic pH value is established in the washing liquid. When rinsing following washing, the acidic or basic treatment liquid can not be completely removed. This is especially true for the bound in the laundry treatment liquid, the so-called bound liquor. In order to neutralize the bound treatment liquid after rinsing, the procedure has hitherto been to use neutralizing agent in an estimated amount or on the basis of empirical values. That's how it is EP 0 287 761 It is known to measure the amount of the additive to be neutralized in the washing liquid and, if appropriate, to add neutralizing agent to the washing liquid. Besides, it is off DE 10 2011 015 188 A1 It is known that to measure a reusable washing liquid, a sample is taken from the washing liquid at which the Measurement is performed. As a rule, an overdose of the neutralizing agent takes place. This results in a change in the pH of an acidic in a basic environment or vice versa, so that no more adequate neutralization occurs. In addition, an overdose of neutralizing agents leads to environmental pollution and unnecessarily high costs.

The invention has for its object to provide a method for the wet treatment of laundry, which leads with the least possible amount of neutralizing agents to a complete or at least almost complete neutralization.

A serving to solve this problem method has the measures of claim 1. Accordingly, it is provided to remove at least one sample from the liquid supplied to the laundry after rinsing. The sample is filtered and only then the pH of the filtered sample is measured. If the measurement results in an acidic or basic pH, neutralizing agent is selectively added to the liquid. In this way, the pH of the liquid of the laundry can be selectively adjusted to a neutral pH after rinsing. Preferably, with the method according to the invention, a regulation of the pH of the liquid can take place in such a way that a pH-neutral or substantially pH-neutral liquid results.

According to the method, it is preferably provided to repeatedly take samples of the liquid supplied to the items of laundry after rinsing. Each sample is first filtered and then the pH of each sample is determined from the filtered sample. It can be determined by comparing several samples, the change in pH. In particular, it can thus be determined how the pH changes due to the added neutralizing agent. The adjustment of the pH value or the neutralization of the liquid added to the laundry after rinsing can thus be set or adjusted iteratively, one after the other, in a stepwise manner. It is preferred that only small amounts of neutralizing agent are added to the liquid, until such time as a neutral pH indicative of complete or near complete neutralization is obtained from the subsequently measured samples. Overdoses of the neutralizing agent or even a change of the pH from an acidic pH to a basic or vice versa are thus effectively avoided.

An advantageous development of the method provides that the pH of at least two successive samples is not started until the targeted addition of at least one neutralizing agent is initiated. In this way, the neutralization begins only when the rinsing process abducted, still bound in the washing rinse liquid has sufficiently mixed with the liquid supplied after rinsing the laundry, so that the the sample taken from the liquid corresponds to the actual pH of the liquid with the rinsing liquid still bound in the items to be washed. Then, the measured pH value of the liquid with the bound rinsing liquid mixed therein from the laundry provides a reliable value for the subsequent neutralization. While the neutralization is taking place, further continuous sampling of the liquid will determine how much neutralization has progressed and the addition of further neutralizing agent will cease when a neutral pH has been measured.

In the advantageous method, the samples are filtered, preferably all of the samples of the liquid, before the pH measurements. The filtration is preferably a fine filtration or microfiltration. Optionally, a very fine filtration can take place. By at least finely or finely filtering the samples, removal of possibly pH-measuring components from the sample occurs. The filtered sample thus allows an accurate pH measurement. Above all, it is prevented that accompanying substances in the samples adversely affect the measuring technology or measuring apparatus or measuring sensors and could falsify the measurement result.

According to a preferred embodiment of the method, the sampling of the liquid added after rinsing the laundry takes place via a bypass. Preferably, a small amount of sample liquid, in particular a small measurement volume flow, is withdrawn through the bypass. The bypass allows continuous sampling.

It is preferably provided, after the addition of preferably small amounts of at least one neutralizing agent, to repeatedly take samples of the liquid together with the neutralizing agent already added to the laundry after rinsing. These samples are also filtered, in particular finely filtered, before their pH is measured. If the pH value measurement of the sample taken last still gives an acidic or basic pH, that is to say complete neutralization, small amounts of neutralizing agent are still added to the liquid and at least one further pH measurement is then carried out. Only when the pH measurement of the last sample has shown that the neutralization has occurred or the liquid has been adjusted substantially to a neutral pH, the neutralization process is terminated and no further samples taken. There is thus a stepwise, controllable, preferably automatically regulated, neutralization.

According to the method, it is preferably provided that either fresh water and / or recirculated water is used as the liquid added after rinsing the laundry. The recirculated water is, for example, water which is produced during the dehydration of the laundry following neutralization, namely so-called press water or else drainage liquid. This contains already neutralized water or neutralized liquid, which can also be used to dilute after flushing the laundry in the same still existing acidic or basic washing liquid and then to neutralize. It is also conceivable to add both fresh water and recycled water or recycled liquid after rinsing and before the start of the neutralization process of the laundry. As a result, the fresh water requirement for neutralizing can at least be reduced.

Another preferred development of the method provides for the removal of samples and / or the metered addition of at least one neutralizing agent when the laundry is moving in the liquid. The rinsing liquid bound in the laundry is thus rinsed out of the laundry by the liquid added after rinsing, in particular pH-neutral liquid, and mixed with the liquid added after rinsing. In this case, dilution of the bound rinsing liquid takes place with the pH-neutral liquid having a much larger volume. The added pH-neutral liquid mixed with the still acidic or basic bound rinse liquid can then be effectively neutralized.

Furthermore, it is preferably provided to wash, rinse and neutralize the laundry in a continuous washing machine with a successive chambers having, rotating drivable drum. In the drum, which is also rotationally driven during neutralization, there is a movement or mixing of the pH-neutral liquid with the laundry and the bound rinsing liquid contained therein.

According to a further advantageous embodiment of the method, it is provided to remove the samples from the chamber of the continuous washing machine in which the neutralization of the laundry is also carried out, preferably a stationary outside drum assigned to this chamber. This is preferably done by a bypass line. The bypass line allows a continuous removal of a measuring volume flow, namely a relatively small amount of sample liquid. By the neutralization takes place in at least one separate chamber of the continuous washing machine, wherein the drum is driven during the neutralization just as rotating as washing and rinsing the laundry, it comes in the neutralization to an intensive movement and mixing of the laundry in the liquid to be neutralized. In the case of neutralization, the washing in the liquid is preferably also brought about by a rotating drive of the drum of the continuous washing machine. In this case, the at least one chamber for performing the neutralization of the laundry as well as the other chambers for washing and rinsing the laundry rotates. This also contributes to an effective neutralization, wherein the samples taken have a representative pH due to the intensive mixing of the added after rinsing the laundry pH-neutral liquid with the rinsed from the washing from the rinse, bound rinse liquid.

Fig. 1

eine schematische Seitenansicht einer Durchlaufwaschmaschine mit einer Probenentnahme- und pW-Wert-Messeinrichtung, und

Fig. 2

einen Querschnitt durch diejenige Kammer der Durchlaufwaschmaschine, in der eine Neutralisation stattfindet mit der Einrichtung zur Probenentnahme, Filtration und pH-Wert-Messung der Probe.

A preferred embodiment of the invention will be explained in more detail with reference to the drawing. In this show:

Fig. 1

a schematic side view of a continuous washing machine with a sampling and pW value measuring device, and

Fig. 2

a cross section through the chamber of the continuous washing machine, in which a neutralization takes place with the means for sampling, filtration and pH measurement of the sample.

The invention is explained below in connection with the wet treatment of laundry in commercial laundries by means of a continuous washing machine 10. In the continuous washing machine 10, washing, rinsing and aftertreatment, in particular neutralization, of the laundry take place. The laundry can be any laundry, specifically flat linen, clothing, in particular workwear, but also mats and the like.

The in the Fig. 1 schematically illustrated continuous washing machine 10 has a about a preferably horizontal axis of rotation rotating or pivoting (reciprocating) drivable drum 11. The laundry to be washed is transported in pieces in the direction of passage 12 through the rotating or pivoting cylindrical drum 11, based on the Presentation in the Fig. 1 from left to right right. In the drum 11 a plurality of successive chambers 14 are formed by transverse partitions 13 in the direction of passage 12. The chambers 14 may be the same size, but also different sizes. The in the Fig. 1 shown continuous washing machine 10 has thirteen consecutive chambers 14. However, the invention is not limited thereto. The invention is also suitable for continuous washing machines 10 having a larger or smaller number of successive chambers 14.

The continuous washing machine 10 shown has three treatment zones successive in the direction of passage 12, namely a prewash zone 15, a final wash zone 16 and a rinse zone 17. A neutralization zone is integrated into the rinse zone 17. In the continuous washing machine 10 shown here, the neutralization zone is formed by a single chamber 14 of the continuous washing machine 10, namely a neutralization chamber 18. The neutralization chamber 18 is the last chamber 14 of the rinsing zone 17 seen in the passage direction 12 and also the last chamber 14 at the same time the continuous washing machine 10.

The rotationally drivable drum 11 of the continuous washing machine 10 are associated with a plurality of stationary and liquid-impermeable outer drums 19 to 23. A first outer drum 19 seen in the direction of passage 12 is located at the end of the prewash zone 15. A second outer drum 20 is arranged at the beginning of the final wash zone 16. In addition, the final wash zone 16 has a third outer drum 21 at the end. A fourth outer drum 22 is located at the beginning of the rinse zone 17 and a fifth (last) outer drum 23 at the end of the rinse zone 17. This outer drum 23 is associated with the neutralization chamber 18 at the end of the continuous washing machine 10.

In front of the drum 11 is a loading chute 24, whereby a loading of the continuous washing machine 10 is carried out by the dirty laundry passes through the loading chute 24 in the first chamber 14 of the prewashing zone 15. At the end of the continuous washing machine 10 is a discharge chute 25. About the discharge chute 25 leaves the washed, rinsed and neutralized laundry the neutralization chamber 18 of the continuous washing machine 10. From the unloading chute 25, the washed, rinsed and neutralized laundry with it still bound neutralized liquid, the tied fleet, a dewatering device, such as a dewatering press or a Zetrifuge be supplied.

From a lowest point of the neutralization chamber 18 associated outer drum 23 is a bypass line 26 goes out. This is a sampling line, which preferably a small amount or a small volume flow of the liquid (sample liquid) of the neutralization chamber 18 can be removed. A pump 28 is located in the bypass line 26. In the flow direction 27 of the sample liquid pumped by the pump 28 through the bypass line 26, a filter 29 follows the pump 28. The filter 29 is preferably a fine filter for fine filtration or a microfilter for microfiltration the sample liquid. It can also be a fine filter. The filter 29 is associated with a discharge line 30 for filtered out of the sample liquid substances or particles. In the flow direction 27 of the sample liquid is followed by the filter 29, a pH-measuring device 31. It is such a pH-measuring device 31, the pH in the filtered sample liquid during the flow of the same through the pH -Messeinrichtung 31 determined. The bypass line 26 is returned by the pH value measuring device 31 to the outer drum 23 of the neutralization chamber 18. In the flow direction 27 of the sample liquid behind the pH value measuring device 21 located portion of the bypass line 26, a branch 32 is provided to a drain line 33. The drain line 33 may, for example, lead to an outflow. By a valve associated with the branch 32, the sample liquid can be passed back to the neutralization chamber 18 or into the discharge line 33 after passing through the pH value measuring device 31.

The neutralization chamber 18 is associated with a supply for at least one neutralizing agent. In addition, a metering device, not shown, is provided for the at least one neutralizing agent. The metering device can be integrated into the pH-value measuring device 31, specifically a controller for the amount of the neutralizing agent to be metered. A liquid neutralizing agent or a neutralizing agent dissolved in a liquid is preferably used. This can be supplied together with the at least one neutralizing agent and the measured sample liquid via the bypass line 26 of the neutralization chamber 18 of the continuous washing machine 10. However, it is also conceivable to feed at least one neutralizing agent to another, not shown point of the neutralization chamber 18. This may be the case, for example, if a solid neutralizing agent is used. There, where the neutralizing agent of the neutralization chamber 18 is supplied, then there is also the metering device. The controller can then be assigned to the metering device or integrated into it. The controller for the amount of However, neutralizing agent to be added can also be located elsewhere, for example, associated with the pH-value measuring device 31 or integrated into it.

The inventive method is described below with reference to the Fig. 1 and 2 the drawing explained in more detail:

In the rotating or pivoting driven drum 11 of the continuous washing machine 10 several laundry items are prewashed, clear washed, rinsed and neutralized in the neutralization chamber 18 at the same time.

The respective laundry item is transferred from the second (middle) chamber 14 of the rinsing zone 17 with the free and in the laundry bound rinsing liquid in the neutralization chamber 18. The free rinsing liquid is then discharged from the outer drum 23 of the neutralization chamber 18, so that the rinsing liquid (bound liquor) bound in the laundry remains only in the laundry item. Subsequently, the neutralization chamber 18 is filled with preferably pH-neutral liquid. This may be fresh water or else recirculated water or other recirculated pH-neutral liquid, for example dehydration liquid which has been separated from the laundry during the dewatering following the neutralization and has been temporarily stored in a memory, not shown.

While in the other chambers 14, the pre-washing, clear washing and rinsing other laundry items is carried out during the rotating or pivoting drive of the drum 11, the laundry of the pH-neutral liquid in the neutralization chamber 18 rinses and thereby bound in the wash rinse the laundry with the supplied pH neutral liquid, the neutralizing liquid, by the movement of the laundry in the same mixed.

Immediately after the supply of the liquid to the neutralization chamber 18, a small partial flow of the liquid as sample liquid is withdrawn from the neutralization chamber 18 via the bypass line 26 in the flow direction 27. This is preferably carried out continuously so that sample liquid can be continuously withdrawn from the neutralization chamber 18 via the bypass line 26 during the movement of the wash of the liquid in the neutralization chamber 18.

During the initial mixing of the bound rinsing liquid in the laundry with the supplied pH neutral liquid still no neutralization takes place Addition of neutralizing agent instead. However, during the mixing of the supplied pH-neutral liquid with the bound rinsing liquid without the addition of neutralizing agent, the running, preferably at regular intervals, pH of the sample liquid is determined. With increasing mixing of the originally pH-neutral liquid supplied with the washing liquid bound in the washing, a constant pH value is established in the samples of the sample liquid as the duration of the movement of the laundry in the supplied liquid increases. As soon as this is the case, ie the continuously measured pH of the sample liquid no longer changes or no longer changes significantly, the neutralization process begins.

Depending on the measured pH value of the bound rinsing liquid mixed with the liquid, namely the sample liquid, successive, preferably in small amounts, corresponding neutralizing agent of the liquid mixed with the bound rinsing liquid of the neutralization chamber 18 is supplied. In this case, the pH value changing in the sample liquid is continuously measured by the supply of small amounts of neutralizing agent. The addition of small amounts of neutralizing agent is continued until the measurement shows that the sample liquid has a neutral or nearly neutral pH, that is, the neutralization of the liquid in the neutralization chamber 18 is completed.

It is conceivable that just before the end of the neutralization process, the intervals of the supply of neutralizing agent are changed, preferably increased, and / or the amount of the at least one added neutralizing agent is reduced. Thus, it can be reliably determined in the final phase of the neutralization process, whether a neutral pH value has been established during the mixing of the laundry with the liquid and the added neutralizing agent and an exact control or regulation of the neutralization process takes place.

The sample liquid is pumped by the pump 28 continuously in the flow direction 27 through the bypass line 26. As seen in the flow direction 27 behind the pump 28, the sample liquid flows through the filter 29, preferably fine or ultra-fine filter. In this the sample liquid is filtered. This is preferably a fine filtration, a microfiltration or microfiltration. The sample liquid filtered by the filter 29 subsequently flows in the flow direction 27 through the pH-value measuring device 31. In this process, successive samples of the sample liquid are measured with regard to the pH. This measurement takes place in successive time intervals, preferably in short successive time intervals. The time intervals may be the same, but may become longer as the neutralization progresses. By taking place at successive intervals measuring the pH of the sample from the sample liquid is a quasi-continuous pH measurement.

The sample liquid leaving the pH value measuring device 31 in the flow direction 27 can optionally be led to a drain via the drain line 33 or can also be returned to the neutralization chamber 18 via the bypass line 26.

The metered addition of the at least one liquid or liquefied neutralizing agent can take place in the region of the pH-value measuring device 31. However, it is also conceivable for at least one neutralizing agent to be fed directly to the neutralization chamber 18 at any other suitable location.

The addition of the at least one neutralizing agent to the sample liquid returned to the neutralization chamber 18 or the direct addition of the at least one neutralizing agent to the liquid in the neutralization chamber 18 takes place by means of a metering device (not shown). The metering device is controlled or regulated by a corresponding actuating means, depending on the pH value which the pH value measuring device 31 has determined. For this purpose, the metering device or the pH value measuring device 31 is assigned a control or regulation, in particular in the form of a computer.

The method according to the invention can be used not only in connection with the continuous washing machine 10 shown in the figures, but also with any continuous washing machine of any structure, in particular any number of chambers 14. The method according to the invention can also be used with other washing machines for commercial laundries, for example washing machines. Throwers.

LIST OF REFERENCE NUMBERS

10

Tunnel washer

11

drum

12

Throughput direction

13

partition wall

14

chamber

15

prewash

16

Wash zone

17

rinse zone

18

Neutralization chamber

19

external drum

20

external drum

21

external drum

22

external drum

23

external drum

24

loading chute

25

discharge chute

26

bypass line

27

flow direction

28

pump

29

filter

30

discharge line

31

pH measuring device

32

junction

33

drain line

Claims (10)

1. A method for the wet-treatment, preferably the washing, of laundry, wherein the laundry is first washed and rinsed and, after rinsing, a neutralization of the laundry is carried out in that neutralizing agent is added as necessary to the liquid in which the laundry is located and/or which is bound in the laundry, characterized in that at least one sample is taken from the liquid, the sample is filtered and at least one pH value of the filtered sample is measured, with neutralizing agent being added as necessary to the liquid in a targeted manner based on the pH value of the liquid obtained from the measurement.
2. The method according to Claim 1, characterized in that samples are repeatedly taken from the liquid, the samples are respectively filtered and the pH value of each filtered sample is determined.
3. The method according to Claim 1 or 2, characterized in that when there is no change, or no significant change, in the pH value of at least two successive samples, the targeted addition of at least one neutralizing agent commences.
4. The method according to one of the previous claims, characterized in that the samples are removed, preferably continuously, through a bypass line (26), in particular after the addition of at least one neutralizing agent to the liquid in which the laundry is located, samples are repeatedly taken from the liquid together with the added neutralizing agent, filtered, the pH value measured and neutralizing agent added as needed until a neutral pH value is measured.
5. The method according to one of the previous Claims, characterized in that, following the rinsing of the laundry, pH neutral liquid is added, in particular fresh water and/or recycled water, preferably dewatering liquid accumulated during the water-removal process which follows neutralization.
6. The method according to one of the previous Claims, characterized in that the taking of the samples and/or the metered addition of neutralizing agent is carried out as the laundry is being agitated in the liquid.
7. The method according to one of the previous Claims, characterized in that the filtration of the samples is conducted as fine filtration, micro-filtration or finest filtration.
8. The method according to one of the previous Claims, characterized in that the laundry is washed, rinsed and neutralized in a tunnel-type washing machine (10) having a rotating or swivelling drum (11) with successive chambers (14, 18), wherein neutralization is carried out after rinsing, preferably in the region of a rinse zone (17) or following the rinse zone (17), preferably in a last chamber, configured as a neutralization chamber (18), of the tunnel-type washing machine (10) and/or in the last chamber of the rinse zone (17).
9. The method according to one of the previous Claims, characterized in that the samples are taken, preferably through a bypass line (26), from the chamber of the tunnel-type washing machine (10) in which the neutralization of the laundry is carried out, in particular from the neutralization chamber (18), preferably from a stationary outer drum (23) of same.
10. The method according to one of the previous Claims, characterized in that during neutralization the laundry is agitated in the liquid by a rotating drive of the drum (11) of the tunnel-type washing machine (10) that contains the chambers (14, 18).

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